Doctor blade apparatus

Abstract

A doctor blade apparatus is attached to a doctor whose doctor blade is pressed against a metering roller provided in an inking train of a printing apparatus and scrapes off an excess portion of ink transferred onto the circumferential surface of the metering roller. The doctor blade apparatus comprises a blade holder attached to a base which moves toward and away from the metering roller, a doctor blade held by the blade holder and extending along substantially the entire axial length of the metering roller, and an elasticity-modifying member which abuts, along the longitudinal direction of the doctor blade, a deflection-side surface of the doctor blade whose edge is pressed against the circumferential surface of the metering roller and deflects accordingly. The elasticity-modifying member is movable toward and away from the edge of the doctor blade. A reciprocal movement mechanism reciprocally moves the elasticity-modifying member toward and away from the edge of the doctor blade. A plurality of elasticity-modifying members may be provided for a single doctor blade along the axial direction of the metering roller and may be adapted to be movable independently of each other.

What is claimed is: 
     
       1. A doctor blade apparatus in which a doctor blade is pressed against a metering roller provided in an inking train of a printing apparatus and scrapes off an excess portion of ink transferred onto a circumferential surface of the metering roller, comprising: a blade holder attached to a base which moves toward and away from the metering roller;   a doctor blade held by said blade holder and extending along substantially the entire axial length of the metering roller;   an elasticity-modifying member abutting, along the longitudinal direction of said doctor blade, a deflection-side surface of said doctor blade whose edge is pressed against the circumferential surface of the metering roller and deflects accordingly, said elasticity-modifying member being reciprocally movable toward and away from the edge of said doctor blade; and   reciprocal movement means for reciprocally moving said elasticity-modifying member toward and away from the edge of said doctor blade.   
     
     
       2. A doctor blade apparatus according to claim 1, wherein said elasticity-modifying member is in the form of a plate held, together with said doctor blade, by said blade holder and restrictedly guided for reciprocal movement toward and away from the edge of said doctor blade, and wherein said reciprocal movement means is reciprocally driving means provided on said blade holder and directly linked to said elasticity-modifying member.   
     
     
       3. A doctor blade apparatus according to claim 1, wherein said elasticity-modifying member is in the form of a plate held, together with said doctor blade, by said blade holder and restrictedly guided for reciprocal movement toward and away from the edge of said doctor blade, and wherein said reciprocal movement means comprises a reciprocally moving member whose tip is linked to said elasticity-modifying member and which can move reciprocally toward and away from the edge of said doctor blade, and reciprocally driving means for reciprocally driving said reciprocally moving member toward and away from the edge of said doctor blade.   
     
     
       4. A doctor blade apparatus according to claim 1, wherein said elasticity-modifying member is of a narrow form extending in the longitudinal direction of said doctor blade and abuts merely a projected edge portion of said doctor blade held by said blade holder, and wherein said reciprocal movement means comprises a reciprocally moving member whose tip is linked to said elasticity-modifying member and which can move reciprocally toward and away from the edge of said doctor blade, and reciprocally driving means for reciprocally driving said reciprocally moving member toward and away from the edge of said doctor blade.   
     
     
       5. A doctor blade apparatus according to claim 2, wherein said reciprocally driving means comprises a cam mechanism. 
     
     
       6. A doctor blade apparatus according to claim 3, wherein said reciprocally driving means comprises a screw mechanism. 
     
     
       7. A doctor blade apparatus according to claim 4, wherein said reciprocally driving means comprises a screw mechanism. 
     
     
       8. A doctor blade apparatus according to claim 4, wherein said reciprocally driving means comprises a piezoelectric actuator. 
     
     
       9. A doctor blade apparatus according to claim 4, wherein said reciprocally driving means comprises an ultrasonic linear motor. 
     
     
       10. A doctor blade apparatus in which a doctor blade is pressed against a metering roller provided in an inking train of a printing apparatus and scrapes off an excess portion of ink transferred onto a circumferential surface of the metering roller, comprising: a blade holder attached to a base which moves toward and away from the metering roller;   a doctor blade held by said blade holder and extending along substantially the entire axial length of the metering roller;   a plurality of elasticity-modifying members abutting, along the longitudinal direction of said doctor blade, a deflection-side surface of said doctor blade which extends along substantially the entire axial length of the metering roller and whose edge is pressed against the circumferential surface of the metering roller and deflects accordingly, said elasticity-modifying members being reciprocally movable toward and away from the edge of said doctor blade independently of each other; and   reciprocal movement means for reciprocally moving said elasticity-modifying members toward and away from the edge of said doctor blade independently of each other.   
     
     
       11. A doctor blade apparatus according to claim 10, wherein said elasticity-modifying member is in the form of a plate held, together with said doctor blade, by said blade holder and restrictedly guided for reciprocal movement toward and away from the edge of said doctor blade, and wherein said reciprocal movement means is reciprocally driving means provided on said blade holder and directly linked to said elasticity-modifying member.   
     
     
       12. A doctor blade apparatus according to claim 10, wherein said elasticity-modifying member is in the form of a plate held, together with said doctor blade, by said blade holder and restrictedly guided for reciprocal movement toward and away from the edge of said doctor blade, and wherein said reciprocal movement means comprises a reciprocally moving member whose tip is linked to said elasticity-modifying member and which can move reciprocally toward and away from the edge of said doctor blade, and reciprocally driving means for reciprocally driving said reciprocally moving member toward and away from the edge of said doctor blade.   
     
     
       13. A doctor blade apparatus according to claim 10, wherein said elasticity-modifying member is of a narrow form extending in the longitudinal direction of said doctor blade and abuts merely a projected edge portion of said doctor blade held by said blade holder, and wherein said reciprocal movement means comprises a reciprocally moving member whose tip is linked to said elasticity-modifying member and which can move reciprocally toward and away from the edge of said doctor blade, and reciprocally driving means for reciprocally driving said reciprocally moving member toward and away from the edge of said doctor blade.   
     
     
       14. A doctor blade apparatus according to claim 11, wherein said reciprocally driving means comprises a cam mechanism. 
     
     
       15. A doctor blade apparatus according to claim 12, wherein said reciprocally driving means comprises a screw mechanism. 
     
     
       16. A doctor blade apparatus according to claim 13, wherein said reciprocally driving means comprises a screw mechanism. 
     
     
       17. A doctor blade apparatus according to claim 13, wherein said reciprocally driving means comprises a piezoelectric actuator. 
     
     
       18. A doctor blade apparatus according to claim 13, wherein said reciprocally driving means comprises an ultrasonic linear motor.